Light in the night

Night before last I woke up about 3:00 a.m. That's what happens when I take a late nap.
My eyes just wouldn't stay shut while I was trying to go back to sleep. Staring through the bedroom door and down the hall I finally realized that instead of pure blackness, I was seeing a pale, grayish blue light. It was so indistinct that I thought maybe it was something making a connection in my brain. (I've seen those computer generated pictures of a nervous impulse dashing around between synapses on the way to the next neuron inside a virtual head.) This was not a reflection or a steady light but a pulsating "thing."
Thoughts of spirits, supernatural events and other things crossed my mind. The more I looked I realized I was counting the seconds between the light and the darkness.

Four seconds. What could this be? There is nothing electronic in the larger bathroom and that seemed to be the source. Finally, I got up and approached the door. . .I could see it more plainly and it seemed to be coming from the top of the medicine cabinet. I turned on the light.
There it was. One of those automatic air fresheners that emit some kind of odor that is supposed to mask other odors. L. had bought it and put it up, out of sight unless you are staring at the ceiling.
Later he said that the battery must be low. After new batteries were installed, it still blinks. From now on, I'm closing that door at bedtime.